1、UDC 678.074 : 678.4 : 620.1 :539.217.5 DEUTSCHE NORM October 1992 Determination of permeability of rubber to gases DIN - 53 536 Prfung von Kautschuk und Elastomeren; Bestimmung der Gasdurchlssigkeit Supersedes February 1985 edition. In keeping with current practice in standards published by the Inte
2、rnational Organization for Standardization (ISO), a comma has been used throughout as the decimal marker: See Explanatory notes for connection with International Standard IS0 1399:1982 and draft International Standard ISO/DIS 2782 published by the International Organization for Standardization (ISO)
3、. 1 Q is the permeability coefficient; This standard describes a method for determining the A is the effective area of the test piece; permeability of rubber to gases at various differential b is the test piece thickness; pressures. Permeability is expressed by the p2 is the pressure of the gas diss
4、olving into the permeability coefficient, which is a function of tempera- test piece; pi is the pressure of the gas which has ture and the type of gas used but not of pressure. Acceptance tests for materials for which the relation- permeated the test piece; ship between permeability and temperature
5、is not t is the time for change in gas volume; known should be carried out at several temperatures. The volume is thus directly proportional to the time Scope and field of application 2 Concept According to T. Graham l, permeation - the passage of a gas through a solid specimen - is a process which
6、takes place in three phases: 1. dissolution of a gas in the specimen; 2. diffusion of the dissolved gas through the spec- 3. evaporation of the gas from the specimen. imen; Since permeation is a mass transfer process, it is dependent on temperature. The permeability coefficient is therefore also a f
7、unction of the temperature, and indicates the rate of volume flow of gas under steady- state conditions through a test piece of a known area and thickness, over a given time period, and when subjected to a given pressure. The differential equations which describe permeation are presented in many tex
8、tbooks 2, 3. For test pieces with parallel flat surfaces, with one surface being subjected to a constant pressure p2 pi under steady-state conditions, equation (1) applies: where V is the volume of gas which has permeated the test piece; -. . lapse. The permeability coefficient for a specific materi
9、al is given by equation (2): V h When testing a gas mixture in which the components have a different degree of solubility in rubber, there might be a departure from linearity in the tirneholume change curve. 3 Designation Designation of the method for determining the per- meability of rubber to gase
10、s (A): Test DIN 53536 - A 4 Apparatus 4.1 Test cell Any equipment may be used which allows the gas pressures and test temperatures in both chambers to be kept constant and the permeated gas volume to be measured. A diagram of a simple apparatus for testing the permeability of test pieces with parall
11、el flat surfaces is provided in the figure on page 2. Continued on pages 2 to 5. Beuth Vedag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). DIN 53 536 Engl. Price group 6 07.95 Sales No. 0106 COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Info
12、rmation Handling ServicesPage 2 DIN 53 536 Conditioning fluid outlet Pressure gauge Thermometer , 1 rJ Conditioning fluid - Test gas Flange c Valve Flange Test piece support Absoi rbent paper / Conditioning fluid inlet Thermometer Figure: Schematic diagram of an apparatus for testing permeability in
13、let The test piece shall be securely clamped between the test cell flanges to ensure gas-tightness. The gas shall enter chamber K2 through the inlet valve, the gas pressure being monitored with a pressure gauge. The test piece shall be supported by a permeable packing piece in chamber K, so that the
14、 test piece does not become deformed due to the force exerted by the gas pressure. A piece of absorbent paper shall be placed between the support and the test piece. The effective area of the test piece, A, shall be equal to the free area between the clamps which is exposed to the the gas in chamber
15、 K,. A graduated, calibrated U-tube filled with a liquid of a given density shall be attached to chamber K,. 4.2 System for conditioning the test cell In order to be able to condition the test cell, the use of a cell with double walls between which a pre-treated heating or cooling fluid can be circu
16、lated is recom- mended (see figure). Since the temperature of the gas in the U-tube is independent of test cell temperature, the U-tube shall be brought to a separate temperature (ambient temperature) to be kept constant to within f 1 OC. 4.3 Device for measuring test piece thickness As specified in
17、 DIN 53 534. 5 Test pieces 5.1 Test piece form The method for forming the test pieces (e.g. whether they are moulded or cut) depends upon the properties of the material used. It is recommended that the test pieces have parallel flat surfaces which are smooth and clean; use of other forms shall be in
18、dicated in the test report. 5.2 Test piece dimensions The test pieces shall have an effective area of at least 8 cm2 and a thickness ranging from 0,l mm to 3 mm. 6 Procedure 6.1 Measuring test piece thickness Before testing, the thickness of the test piece shall be determined by taking the mean of m
19、easurements taken at not less than six places, using method Al as spec- ified in DIN 53 534. 6.2 Clamping the test piece The test piece shall be placed on a support with a piece of absorbent paper between the test piece and support, and then clamped in place between chambers K, and K,. Gas-tightness
20、 shall be determined by fill- ing chamber K2 with the test gas and bringing the gas to the desired pressure, using the pressure gauge to monitor the pressure. NOTE: If a test gas is used which reacts with air, both chambers shall be flushed with the gas before testing. 6.3 Conditioning the test piec
21、e The test piece is at test temperature when the condi- tioning fluid temperatures measured at the fluid inlet and outlet valves are identical (see figure). Test piece temperature shall be kept constant to within f 1 “G. 6.4 Measuring permeability to gas Once the test piece has reached test temperat
22、ure, test- ing can begin. The gas which permeates the test piece displaces the level of the liquid, or meniscus, in the U- tube. The measured gas volume, V, can be plotted as a function of time t at constant temperature 6 in a COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Inf
23、ormation Handling ServicesDIN 53 536 Page 3 time/volume change curve. During the initial diffusion stage (represented by the non-linear portion of the curve), a concentration of gas builds up in the test piece as the test gas displaces the air in, and then dif- fuses through, the test piece before r
24、eaching steady- state conditions (represented by the linear portion of the curve). This linear portion only shall be taken into consideration when calculating the permeablity coeffi- cient. To avoid inaccurate results, the U-tube shall be filled with a liquid which does not dissolve the test gas and
25、 which has a low vapour pressure at temperature 8?. The recommended test temperature is 30C; other test temperatures shall be indicated in the test report. When testing over a range of temperatures, measurements shall be taken at a minimum of four temperatures. 7 Evaluation The permeability coeffici
26、ent, Q, given in m2 * s-? * Pa-?, shall be calculated using equation (3) for each test piece temperature, taking pairs of values for AV, and At from the time/volume change curve. NOTE: Since the gas in chamber KI is at a pressure greater than atmospheric pressure pl (as a result of the difference be
27、tween the menis- ci in both limbs of the U-tube), and since the temperature of the permeated gas in the U-tube is at ambient temperature, the measured volume V, must be corrected to standard reference conditions when calculating the gas volume, V 4 (see table 1 for corrections). where b A P2 P1 VU A
28、t AU e AL placed the meniscus over At seconds; is the test piece thickness, in m; is the effective area of the test piece, in m2; is the pressure in chamber K, in Pa; is atmospheric pressure, in Pa; is the gas volume, in m3, filling chamber K, and the U-tube at the beginning of the test; is the time
29、 for change in gas volume, in s; is the U-tube cross-sectional area, in m2; is the density of the liquid in the U-tube, in kg/m3; is the displacement of the meniscus in the U-tube during testing, in m; fiu is the temperature of the gas in the U-tube (ambient temperature), in OC; po is standard press
30、ure (101 325 Pa); To is standard temperature (273,15 K); g is local gravitational acceleration in m/s2, if known, or standard gravitational accelera- tion (g = 9,80665 m/s2). The permeability coefficient derived using this equation shows the volume in m3 of the gas permeating a test piece with a thi
31、ckness of 1 m and a testing surface of 1 m2, over a time period of 1 s, at a differential pres- sure of 1 Pa, and at test piece temperature referring to standard conditions. When testing over a range of temperatures, the per- meability coefficient shall be plotted as a function of the test piece tem
32、perature using equation (4): Q Qo 1g - = f( b) type of test gas; c) thickness, b, of test piece, in m; d) test pressures pi and p2, in Pa; e) test piece temperature, th in OC; f) permeability coefficient, Q, in m2- Pa-? . s-? at temperature 6; g) when testing over a range of temperatures: - temperat
33、ure range; - curve based on equation 4 or 5; h) test date. COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Information Handling ServicesPage 4 DIN 53 536 10,o 10,5 1 l,o 11,5 12,o 12,5 13,O 13,5 14,O 14,5 15,O , in Pa, as a function of au, in “C, and with To = 273 K Table 1 : V
34、alues for po B“+ To TO Q“+ To Po - 7 105 037 105 222 105 408 105 593 105 779 105 964 106150 106 336 106 521 106 707 106 892 6, 153 16,O 16,5 17,O 173 18,O 18,5 19,o 19,5 20,o 6“ + To Po * 7 The value of Q in SI units 107 078 107 264 107 449 107 635 107 820 108 006 108 191 108 377 108 563 108 748 Tab
35、le 2: Conversion table for Q s - bar 8,64 x IO4 d . bar 8,64 x 109 8,64 X lo8 c * bar 20,5 21 ,o 213 22,o 22,5 23,O 23,5 24,O 24,5 25,O Qu i To Po 7 108 934 109119 1 O9 305 1 O9 490 1 O9 676 1 O9 862 110047 110233 110418 110604 QU 25,5 26,O 26,5 27,O 27,5 28,O 28,5 29,0 29,5 30,O 110789 110975 111 1
36、61 111 346 111 532 111 717 111 903 112089 112274 112460 Q Table 3: Conversion table for D(b) = - in SI units s - m2 * Pa s * m2 . bar dm3 8,64 X IO* I 1 d * m2 * bar cm3 s cm2 Pa cm3 s cm2 - bar 1 o2 I 07 COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Information Handling Serv
37、icesDIN 53 536 Page 5 Standards and other documents referred to DIN 53534 Determination of the linear dimensions of rubber test pieces and finished components IS0 1399 : 1982 Rubber, vulcanized; determination of permeability to gases; constant volume method ISO/DIS 2782 Rubber, vulcanized and thermo
38、plastic; determination of permeability to gases l Graham, T. On the absorption and dialytic separation of gases by colloid septa. Phil. Mag., 1866: 32,401 ff. 2 Jost, W. Diffusion (Diffusion). Darmstadt: Verlag Steinkopff, 1957. 3 Stuart, H. Physik der Hochpolymeren (Physics of high polymers). Volum
39、e II. Berlin, Gttingen, Heidelberg: Springer Ver- lag, 1953. 4 Schrfer, W. Bestimmung der Gasdurchlssigkeit von Kunststoffolien (Determining the permeability of plastic film). Kunststoffe, 1956: 46,143 ff. Previous editions DIN 53 536: 09.62,01.80,02.85. Amendments In comparison with the 1985 editio
40、n, statements regarding the dependence of the permeability coefficient on the type of test gas used have been included, and the entire standard has been editorially revised. Explanatory notes This standard has been jointly prepared by Technical Committee 434 Prfung physikalischer Eigenschaften von K
41、aut- schuk und Elastomeren of the Normenausschu Materialprfung (Materials Testing Standards Committee) and by the Normenausschu Kautschuktechnik (Rubber Technology Standards Committee). The determination of permeability to gases is especially relevant for many elastomer-based products such as plasti
42、c film, inner tubes, tubeless tyre liners, balloons and other gas containers, and diaphragms. The permeability coefficient is also significant for theoretical studies of gas diffusion in relation to polymer structure. The test method described in this standard conforms only in substance to the metho
43、ds specified in IS0 1399 :1982 and ISO/DIS 2782, for the following reasons: 1. The permeability coefficient is a material constant and therefore independent of the test method and test piece form. 2. The method described in this standard can be used with less complex equipment (e.g. with a fixed U-t
44、ube) than that described in the IS0 Standards. Thus, older equipment which is still available may continue to be used. All of the above-mentioned methods are suitable for a permeability coefficient range from 1 - lopla to 150 - 10-8m2 s- - Pa-. Natural rubber has a permeability coefficient of 90 10-
45、*m2 s- * Pa-, with the test piece thickness ranging from 10-4m to 3 - 10-3m, the test temperature ranging from 20C to 125”C, and with a differential pressure up to about 500 kPa. International Patent Classification G 05 D 23/00 GO1 L7/00 G O1 M 3/00 G O1 N 15/08 COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Information Handling Services
